Contact-free control of medical imaging systems

ABSTRACT

The present invention pertains to a method and apparatus for contactless control of a medical imaging system. A medical image can be acquired and displayed, and an aspect of the image can be altered based on a tracked position of a user body part. The user can be sensed by a sensing device, and the user body part tracked by a tracking unit in a first processing unit. A second processing unit can be coupled to the first processing unit and can have a control unit for controlling the medical imaging system.

FIELD OF THE INVENTION

The present invention pertains to the field of intraoperative medicalimaging. The present invention also pertains to the field ofhuman-computer interaction for medical imaging.

BACKGROUND

Interventional procedures can be a less invasive alternative to opensurgeries for a growing number of applications. In an interventionalprocedure, a physician can insert a catheter or other implement into apatient through a relatively small incision and perform the procedure,whether it is insertion of a stent, removal of a malignant tissue, orany other manipulation, under image guidance. One type of image guidanceis fluoroscopy, wherein real-time X-ray images are obtained by an X-raytube and fluorescent screen or spatially resolved detector positioned onopposite sides of a patient. However, the dose of ionizing radiationdelivered to patients during a fluoroscopy guided procedure, or otherX-ray intensive imaging procedures, being somewhat of a concern, methodsand apparatuses for dose-reduction have been developed.

A method and apparatus for adaptive exposure in X-ray imaging systemsenable a surgeon to select a “region of interest” (ROI) within theavailable field of view of the X-ray imaging system, which can be imagedat a higher quality than the rest of the field of view. Adaptiveexposure may be implemented in inverse geometry X-ray imaging systemswherein a plurality of discrete source locations, e.g. a scanning beamsource or an array of discrete emitters, illuminate a spatially resolveddetector in rapid sequence. The ROI may be exposed to a higher amount ofX-ray flux to improve image contrast and quality relative to areasoutside the ROI, so that these areas receive only the minimum amount ofradiation necessary for the physician's analysis. ROI selection may becompleted using a stylus or finger on a screen or otherwise tracing outan ROI on the presented X-ray image.

However, an operating room may be held to a high degree of sterility,requiring all objects to meet certain standards; a surgeon may be unableto touch a stylus or screen after beginning a procedure if the stylus orscreen is not sterilized. What is needed is a method and apparatus bywhich a physician may control the ROI being implemented by an imagingsystem or other equipment parameters without risk of contamination ortime-expensive processes during an interventional or otheroperating-room procedure. Embodiments of the present invention utilizean alternative means of human-computer interaction to offer acontact-free method and apparatus for ROI definition and relatedcommands in an operating room.

SUMMARY

The present invention pertains to a method and apparatus for contactlesscontrol of a medical imaging system. A medical image can be acquired anddisplayed, and an aspect of the image can be altered based on a trackedposition of a user body part, such as a hand or wrist. An additionalbody part can also be tracked and utilized in conjunction with the firstbody part to affect a second aspect of the image. A control zone can bedefined a fixed distance from a body reference point, such as the chest,head, or point between the shoulders of the user, or in some otherlocation. Image aspects may be the size or location of a region ofinterest.

The user can be sensed by a sensing device, and the user body parttracked by a tracking unit or units in a first processing unit. A secondprocessing unit coupled to the first processing unit and can have acontrol unit for controlling the medical imaging system and can handlecontrol zone definition. The medical imaging system may utilize aradiation source configured to deliver higher flux to a specified regionof interest than to other regions in its field of view.

These and other objects and advantages of the various embodiments of thepresent invention will be recognized by those of ordinary skill in theart after reading the following detailed description of the embodimentsthat are illustrated in the various drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements.

FIG. 1 is a diagram illustrating the components of one embodiment of thepresent invention.

FIG. 2 is a diagram showing an exemplary control zone of one embodimentof the present invention.

FIG. 3 is a diagram of a direct side view of a tracked body and controlzone of one embodiment of the present invention.

FIG. 4 is a diagram of a direct frontal view of a tracked body andcontrol zone of one embodiment of the present invention.

FIG. 5 is a flow diagram showing steps of one embodiment of the presentinvention that can utilize two-dimensional or three-dimensional sensingor imaging devices.

FIG. 6 is a diagram of one example of a possible simulated ROIappearance of one embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction withthese embodiments, it will be understood that they are not intended tolimit the invention to these embodiments. On the contrary, the inventionis intended to cover alternatives, modifications and equivalents, whichmay be included within the spirit and scope of the invention as definedby the appended claims. Furthermore, in the following detaileddescription of embodiments of the present invention, numerous specificdetails are set forth in order to provide a thorough understanding ofthe present invention. However, it will be recognized by one of ordinaryskill in the art that the present invention may be practiced withoutthese specific details. In other instances, well-known methods,procedures, components, and circuits have not been described in detailas not to unnecessarily obscure aspects of the embodiments of thepresent invention.

FIG. 1 is a diagram illustrating the components of one embodiment of thepresent invention. In FIG. 1, arrows represent transmission ofinformation. It can be seen that information from sensing device 11 canbe transmitted to processing unit 13. Sensing device 11 may be atwo-dimensional imaging device such as any type of digital camera orother digital imaging device. Alternatively, sensing device 11 may be athree-dimensional imaging device such as a set of two cameras providingstereoscopic information or may be a three-dimensional sensing devicesuch as a system comprising a laser or lasers and a detector ordetectors that can determine the distances and hence locations of allobjects in its field of view. Sensing device 11 may also be somecombination of the sensing and imaging devices just mentioned.Processing unit 13 may be a personal computer (PC), computer withWindows operating system, Macintosh, embedded processing unit, or othercomputer or processor. Processing unit 13 can comprise thefunctionalities of tracking unit “B” 15, tracking unit “RH” 16, trackingunit “LH” 17, and optionally additional tracking units 19. Processingunit 13 can also comprise a microprocessor, random access memory or harddisk drive.

Control zone definition 18 can refer to the delineation of ageometrically related set of coordinates fixed relative to the locationof a human body, which can be provided by tracking unit “B” 15. If thecoordinates of the right or left hand(s) or wrist(s), which can beprovided by tracking unit “RH” 16 and tracking unit “LH” 17respectively, coincide with coordinate(s) within the defined controlzone, information passage to another processing block, simulated-ROIcontrol 101, may be activated. Information passed to simulated-ROIcontrol 101 may include the x-, y- and z-coordinates of one or bothwrists of a tracked body, depending on whether one or both of the wristsentered the control zone.

In one embodiment of the present invention, simulated-ROI control 101may be activated by the switch of a Boolean statement, such as “HandEntered Control Zone,” from “false” to “true.” The status of such aBoolean statement may be checked for each set of image or sensed data,e.g. each frame, received from sensing device 11 by processing unit 13through evaluation of the position(s) of relevant tracked body part(s)with respect to boundaries determined by control zone definition 18. Thestatus of such a Boolean statement for a given frame may be stored andaccessed during the processing of the subsequent frame such that aswitch from “false” to “true” can be recognized and activatesimulated-ROI control 101 while a continuation, such as “true” to“true,” may not interfere with simulated-ROI control 101 if alreadyrunning in processing unit 14. Similarly, a change from “true” to“false” may deactivate simulated-ROI control 101, and a continuationsuch as “false” to “false” may not initiate communication withsimulated-ROI control 101.

In an embodiment of the present invention, Boolean statements may beevaluated as described for the positions returned by both tracking unit“RH” 16 and tracking unit “LH” 17. In this embodiment, the specific taskcarried out by simulated-ROI control 101 of processing unit 14 may bedependent on whether one or both statements are “true.”

In some embodiments of the present invention, simulated-ROI control 101may be activated without control zone definition 18. In theseembodiments of the present invention, processing unit 13 may or may notbe utilized prior to activation of simulated-ROI control 101. In oneembodiment, positions of tracked body parts provided by processing unit13 can be monitored for the occurrence of an activation event unrelatedto a control zone, such as the tracing of a certain pattern, amount oftime spent stationary, orientation with respect to one another, or anyother discernible event. A single tracking unit or multiple trackingunits may provide locations from which this type of activation event canbe detected, and one-dimensional, two-dimensional, or three-dimensionallocations may suffice.

In another embodiment of the present invention, control zone definition18 may be replaced by any other type of switch, including but notlimited to a foot pedal, voice command, button, or any other switch orcue, that can turn on simulated-ROI control 101. In this embodiment ofthe present invention, processing unit 13 may be activated along withsimulated-ROI control 101.

Processing unit 14 may both receive information from and transmitinformation to imaging system 12. Imaging system 12 can be an X-rayimaging system, e.g. a fluoroscopic X-ray imaging system, or any otherelectromagnetic radiation-based imaging system, possibly capable ofproviding real-time video. Imaging system 12 may also represent anyimaging or other medical device operated under sterile conditions, orwhere hands-free control may be useful.

Imaging system 12 may be a digital X-ray imaging system or other imagingsystem enabled to provide variable levels of X-ray radiation to regionsof the patient within its field of view according to selection(s) by asurgeon or operator. Region(s) within the field of view that a surgeonor physician selects for higher fidelity, possibly higher exposure,imaging may be referred to as “region(s) of interest” or “ROI(s).” X-rayimaging system 12 may transmit image data to processing unit 14, whichmay display acquired X-ray images on display 102. X-ray imaging system12 may also transmit information containing the current levels of X-rayradiation being delivered to regions within the field of view such thatcurrently implemented ROI(s) can be demarcated on display 102.

Processing unit 14 may contain the functionality of simulated-ROIcontrol 101 such that if it is receiving information from bothprocessing unit 13 and X-ray imaging system 12, the movement ofcoordinates determined by tracking unit “RH” 16 and tracking unit “LH”17, e.g. the coordinates of a body's right and left wrists or hands, maybe used to alter the ROI demarcation(s) on display 102. If the userapproves the alterations, information may be transmitted to X-rayimaging system 12, which can alter exposure levels accordingly.

Processing unit 14 may be a PC, computer with Windows operating system,Macintosh, embedded processing unit, or other computer or processorcomprising the functionalities of control zone definition 18 andsimulated-ROI control 101. Processing unit 13 and processing unit 14 maycomprise two individual processors, a single processor, or more than twoprocessors. Any number of processors or computers may be used toimplement the functionalities (or processing blocks) of processing unit13 and processing unit 14, e.g. tracking, control zone definition, andROI control. It may also be noted that some processing may take placewithin other components of FIG. 1, e.g. image reconstruction withinX-ray imaging system 12 or background subtraction, human bodyextraction, and tracking within sensing device 11.

Depending on the data available from a selected sensing device 11,tracking units may either be implemented in hardware or implementedthrough tracking software. Proper tracking units can be implemented suchthat embodiments of the present invention can track the location(s) of areference body point or body points, e.g. the center of the chest, thehead, or the two shoulders, provided by tracking unit “B” 15 or by somecombination of tracking units, the location(s) of the left and/or righthand(s) or wrist(s) provided by tracking unit “RH” 16 and/or trackingunit “LH” 17 respectively, and/or any other body parts.

Control zone definition 18 may comprise boundaries of a cube, cuboid,sphere, polyhedra, cone, or any other shape. The boundaries of a shapemay be defined as a fixed distance from a central or reference bodypoint, e.g. such that they can move with the tracked body, or in anothermanner. The nearest boundary or center of a shape may be fixed 1 to 6inches, 6 to 12 inches, 12 to 18 inches, 18 to 24 inches, 24 to 30inches, or 30 to 36 inches from a reference body point, or any integeror non-integer number of inches within the enumerated ranges. Forexample, the boundary may be fixed 12″, 13″, 14″, 15″, 16″, 17″, 18″,19″, 20″, 21″, 22″, 23″, 24″, 25″, 26″, 27″, 28″, 29″, or 30″ from areference body point, or any non-integer number of inches between theenumerated values. Such a central body point to which a control zone canbe referenced may be a body point provided by tracking unit “B” 15, suchas the chest of the tracked body. Alternatively, it may be an average ofmultiple body points provided by additional tracking units 19. In oneembodiment of the present invention, the central body point to which thecontrol zone is referenced is the average or some other composite of thepositions of a tracked body's left shoulder, right shoulder, and chest.Since small, false variations in tracked locations, stemming from noiseor otherwise unrelated to true motion, may exist, the position of acontrol zone related to an averaged or composite reference body pointmay be less prone to jitter compared to the position of a control zonerelated to a single, tracked body point.

FIG. 2 is a diagram showing an exemplary control zone of one embodimentof the present invention. It can be seen that control zone 21 can bedefined such that it is a fixed distance from reference body point 23 oftracked body 24. While reference body point 23 may appear in FIG. 2 tobe located on or near the chest of tracked body 24, reference body point23 may be a single tracked location or an average or composite ofsurrounding body locations. In one embodiment of the present invention,control zone 21 can be referenced to reference body point 23 but remainparallel or otherwise oriented with respect to the imaging or sensingdevice 11. For example, tracked body 24 and control zone 21 as shown inFIG. 2 may have been generated by a user standing directly in front ofimaging or sensing device 11 or may have been generated by a userstanding at some angle relative to imaging or sensing device 11.

Referencing control zone 21 to reference body point 23 and orienting itrelative to sensing device 11 is one method of generating aconveniently-positioned control zone with flexibility in systempositioning with respect to the user. This feature may be particularlyuseful if sensing device 11 cannot be positioned directly in front ofthe surgeon during a procedure due to spatial requirements of otherequipment, if the surgeon may need to access the control zone fromvarious laterally spaced locations during the procedure, or for avariety of other reasons. However, any combination of positionreferences and orientations for the control zone may be used. Forexample, control zone 21 may be referenced to a fixed location in spaceincluding but not limited to an operating table, piece of equipment,display 102, or other predetermined point in space. A stationary controlzone may be particularly useful if a surgeon may be placing his or herhands through most of the nearby accessible space during the procedureand therefore prefers to turn toward or step to a different location toaccess the control zone. Another alternative may be for the control zoneorientation to follow the orientation of the tracked body, theorientation of the tracked body possibly being defined by the positionsof the body's chest and shoulders.

The dimensions of a control zone may be selected by the user orautomatically determined. The dimensions of control zone 21, e.g. length25, width 26, and height 27 of control zone 21, may be predetermined ormay be determined by the system based on body tracking parameters. Apredetermined value of height 27 or length 25 may be between zero and 8feet, or any other value, as the field of view of sensing device 11allows. For example, height 27 may be 6 to 12 inches, 12 to 18 inches,18 to 24 inches, 24 to 30 inches, 30 to 36 inches, 36 to 42 inches, 42to 48 inches, 48 to 54 inches, or 54 to 60 inches, inclusive, or anyinteger or non-integer number of inches within the enumerated ranges.Height 27 may further be 18″, 19″, 20″ 21″, 22″, 23″, 24″, 25″, 26″,27″, 28″, 29″, 30″, 31″, 32″, 33″, 34″, 35″, or 36″, or any non-integernumber of integers between the enumerated values. Alternatively, height27 and length 25 may extend across the entire available view of sensingdevice 11. A predetermined value of width 26 may be between zero and 4feet, or any other value. For example, width 26 may be zero to 3 inches,3 to 6 inches, 6 to 12 inches, 12 to 15 inches, 15 to 18 inches, 18 to21 inches, 21 to 24 inches, 24 to 27 inches, 37 to 30 inches, 30 to 33inches, 33 to 36 inches, 36 to 39 inches, 39 to 42 inches, 42 to 25inches, or 45 to 48 inches, inclusive, or any integer or non-integernumber of inches within the enumerate ranges. Width 26 may further be4″, 5″, 6″, 7″, 8″, 9″, 10″, 11″, 12″, 13″, 14″, 15″, 16″, 17″, 18″, 19″20″, 21″, 22″, 23″ or 24″, or any non-integer number of inches betweenthe enumerated values. Alternatively, width 26 may extend from the sideof the control zone nearest the user to the area nearest sensing device11 within its field of view.

As an alternative to predetermined control zone dimensions, the systemmay include further tracking units so that the dimensions of controlzone 21 can be referenced to certain body features; height 27 may extendfrom the top of shoulders 28 to hips 29 of the tracked body, and length25 may extend outwards some fixed distance from the outside of shoulders28. The locations of shoulders 28, hips 29, and any locations used todetermine body metrics may be provided by additional tracking units 19.Any other parameters of a tracked body may be used to define thedimensions of a control zone.

In one embodiment of the present invention, control zone definition 18can comprise creating a control zone by defining eight points that canserve as eight corners of a control zone, e.g. rectangular control zone21. In sets of three or four, the eight points can then be used todefine planes that serve as the outer boundaries of the control zone.Alternatively, fewer than eight or more than eight points can be definedand a control zone delineated by planes including at least three of thedefined points. If a three-dimensional control zone is desired, thenumber of defined points may be four, five, six, seven, eight, nine,ten, eleven, twelve, or more.

Since any shape, e.g. a cube, cuboid, sphere, polyhedra, cone, or anyother shape, may be used for the control zone, control zone definition18 can comprise any one of a number of methods of control zoneconstruction. For example, if a spherical control zone is desired,preliminary definition of a center point and a radius may be preferableto construction via corner points and planes.

An image or video of a simplified, e.g. stick, figure and a control zonemay be provided on display 102. The figure may be relatively complete ifprocessing unit 13 includes a sufficient number of additional trackingunits 19 to construct a full stick-figure of the tracked body, e.g. ahead, shoulders, elbows, knees, and so forth. Alternatively, display 102may display only the locations provided by tracking unit “RH” 16,tracking unit “LH” 17, and/or tracking unit “B” 15, e.g. the location ofthe right hand or wrist, left hand or wrist, and/or reference bodypoint, along with the control zone. Display 102 may display one, two, ormore than two perspectives of tracked body locations and the controlzone. One perspective may be a direct side view, as in FIG. 3, toprovide the user with a clear indication of the distance between his orher hands or wrists and a defined control zone. Another perspective maybe a direct frontal view, as in FIG. 4, so that the user can view the x-and y-coordinate motion of tracked body parts as seen by the sensingdevice 11. Other perspectives, in addition to or instead of direct sideand frontal views, may be provided, including but not limited to viewsfrom 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 degrees, or some numberof degrees between the enumerated values, above or below a directfrontal view, clockwise or counterclockwise from a direct side view, orsome combination thereof.

Other visual cues or indications may be incorporated into views providedon display 102. Control zone 21 may be outlined or shaded with a color,and this color may change according to whether a tracked body part(s)has entered the control zone. For example, the control zone may beoutlined or shaded in one color, e.g. green, when no relevant body partsare inside of the control zone, in a second color, e.g. yellow, when onetracked hand or wrist is inside of the control zone, and in a thirdcolor, e.g. red, when both tracked hands or wrists are inside of thecontrol zone. Such visual cues or indications may aid the user inrealizing when he or she has entered the control zone and activatedsimulated-ROI control 101. The first, second, and third colors may beany color including but not limited to green, red, yellow, purple, blue,orange, white, or black.

Control zone definition 18 may be included in embodiments of the presentinvention in which sensing device 11 is capable of sensing or imagingthree dimensions; two dimensions may be used for simulated-ROImanipulation and a third primarily for activation and deactivation ofsimulated-ROI control 101(via identification of control zone entranceand exit). In embodiments of the present invention in which sensingdevice 11 images or senses two dimensions, activation and deactivationof simulated-ROI control 101 may be accomplished by voice command, afoot pedal, or any other method. Such a trigger may be incorporated inthree-dimensional systems as well. It may serve as a replacement forcontrol zone definition 18 or as a preliminary step which can turncontrol zone 21 on and off as specified by the user. It may be desirablefor the control zone 21 to be turned on and off during a procedure sothat simulated-ROI control 101 cannot be accidentally activated by asurgeon's motions near or in the control zone.

FIG. 5 is a flow diagram showing steps of one embodiment of the presentinvention that can utilize two-dimensional or three-dimensional sensingor imaging devices. Dashed lines around step 51, step 55, step 501, andstep 502 indicate that these steps can be completed by other systems,e.g. sensing device 11 and X-ray imaging system 12.

As previously discussed, the first step for a system utilizing athree-dimensional sensing or imaging system once relevant body locationshave been obtained, may be step 52, defining a control zone. Once thiscontrol zone is defined, the x-, y-, and z-coordinates of tracked bodyparts relative to the defined control zone may be monitored (step 53)such that simulated-ROI control 101 is activated upon detection ofactivation event, e.g. when one or both hands or wrists enter thecontrol zone, as in step 54. For example, the dimensions of simulatedROI 21 may be defined by geometric “if/then” statements relating thepositions of tracked body parts to positions at which simulated-ROIcontrol 101 may be activated.

In the embodiment of FIG. 1, simulated-ROI control 101 may be executedin processing unit 14 and assisted by display 102. A possible connectionbetween processing unit 14 and X-ray imaging system 12 is furtherdetailed in step 58, step 59, step 501, and step 502 of FIG. 5. Asimulated ROI, e.g. an ROI displayed against an X-ray image backgroundsuch as a pre-acquired sequence or video on display 102, can respond touser motions within the control zone, as opposed the ROI being executedby X-ray imaging system 12 responding to every user motion in thecontrol zone. Displaying changes to a simulated rather than actual ROImay allow the user time to view and consider potential changes beforehaving the changes implemented by the X-ray imaging system. Theintermediate step of editing a simulated ROI may also reduce unnecessaryexposure to areas of the patient outside the ROI that may stem from theuser overly enlarging the ROI or moving it over an unintended regionbefore reaching a correct ROI size and position. However, in someembodiments of the present invention, including those that may notutilize ionizing radiation for imaging, the ROI being executed by thesystem may be edited in real time. In the following description,“simulated ROI” may be understood to represent the actual ROI of thesystem for such embodiments.

Steps in FIG. 5 may occur while X-ray imaging system 12 is not activelyacquiring images. During procedures, surgeons may turn X-ray acquisitionon and off to avoid exposing the patient and medical personnel to X-rayradiation during stages of a procedure where X-ray guidance is notnecessary. While acquisition is off, the screen or display of the X-rayimaging system which displays X-ray images or video may continuouslydisplay a previously acquired X-ray image loop. This previously acquiredvideo loop may provide landmarks on which a simulated ROI can be drawnor edited and can be displayed on display 102. Alternatively, a singleframe or short video loop acquired without any ROI being executed by thesystem, e.g. with the system imaging the entire field of view with equalexposure, may be a background over which a simulated ROI may bedisplayed. The latter, i.e. unfiltered, background may be useful if theuser is likely to wish to enlarge or significantly move the ROI duringthe procedure, as all regions of the potential field of view (FOV) willbe visible. The former, i.e. recently acquired, background may bedesirable for other cases, e.g. if the surgeon is likely to shrink ormake small changes to the ROI during the procedure, as editing can bebased on the most current images available.

A simulated ROI may be displayed in a variety of ways. A colored, e.g.green, red, yellow, purple, blue, orange, white, or black, outline maybe drawn around the simulated ROI. An ROI shape may have been selectedby the user prior to activating simulated-ROI control 101 or otherwiseediting the simulated ROI, such that this colored outline can be acircle, square, rectangular, trapezoidal, polygonal, triangular, or anyother preselected shape. The shape and size of the simulated ROI mayrespond to user motions within the control zone. An option may alsoexist for additional or alternative simulated ROI(s) of differentshape(s) than the originally selected simulated ROI to be made availableto the user once the procedure has begun. This option may be beneficialas a user may wish to use an ROI of a different shape once a catheter orother implement has been inserted into a patient.

FIG. 6 is a diagram of one example of a possible simulated ROIappearance of one embodiment of the present invention. In FIG. 6, thepreselected ROI shape is a circle. Background 61 within frame 63represents a grayscale X-ray image of the cardiac region of a patient.Simulated circular ROI 62 has been positioned such that it encompasses aspecific region of the heart and not an extraneous amount of surroundingtissue or other regions of the heart. The outline of simulated circularROI 62 (and any ROI outlines) may be green, red, yellow, purple, blue,orange, white, or black, or any other color with good contrast againstdisplayed image backgrounds, e.g. a grayscale X-ray image background. InFIG. 6, simulated circular ROI 62 is represented with a dashed line,though in embodiments of the present invention it may be representedwith a solid line, dashed line, dotted line, or any other type ofdemarcation.

Step 58 may include the implementation of scaling or othertransformations between tracked movements and changes to the simulatedROI. The correlation between the magnitude of user motions and themagnitude of changes to the simulated ROI may depend on the distancebetween the user and the imaging device as greater distance may causethe motions to appear relatively smaller. If a sensing, e.g. laser andcamera, device is utilized, the actual distance between the tracked bodyand the device may be obtained and accounted for in a correlationmethod. It may also be desirable to allow the correlation to be tunableor adjustable, as variations may exist in user preference regarding theoptimal relationship between hand motion and resultant ROI change(s).

Predetermined “user motion to ROI change” ratios may include but not belimited to 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, and 1:5 or any ratiosbetween the enumerated values. Ratios may also include non-integercomponents such as 3.5:1, 3.25:1, 2.75:1, 2.5:1, 2.25:1, 1.75:1, 1.5:1,1.25:1, and the reverse of all such ratios. However, ratios may behighly dependent on the geometry of the system and carry any othervalues, including above or below 5:1 or 1:5.

Once simulated-ROI control 101 has been enabled simulated ROI editingmay depend only on the changes in x- and y-coordinates of tracked bodyparts between frames. Z-coordinates, if available, may be monitored forthe purpose of turning off simulated-ROI control 101. Alternatively,available z-coordinates may be incorporated into simulated ROI editing.

Changes in the size of a simulated ROI in step 58 may depend on thechange in the relative distance between a tracked left hand or wrist anda tracked right hand or wrist corresponding to a given tracked body inthe view of sensing device 11. The relative distance between the twotracked hands or wrists may be computed for each frame such that changesin the relative distance can be computed on a frame-by-frame basis bysubtracting the relative distance in the present frame from the relativedistance in the previously acquired frame. The relative distance maycomputed as d_(rel)=√{square root over((x_(right)−x_(left))²+(y_(right)−y_(left))²)}{square root over((x_(right)−x_(left))²+(y_(right)−y_(left))²)} where x_(right) andx_(left) are the x-coordinates of the right and left hands or wristsrespectively and y_(right) and y_(left) are the y-coordinates of theright and left hands or wrists respectively. The difference betweenrelative distances in contiguous frames, Δd_(rel), may be scaled by somefactor. Changes to the dimensions of a simulated ROI between frames,possibly shown on display 102, may be based on the absolute or scaledvalue of Δd_(rel) between frames from sensing device 11.

Changes to the location of a simulated ROI in step 58 may be based onuser motion and similarly computed, though a vector, e.g. magnitude withdirection, rather than scalar, e.g. magnitude only, quantity may becomputed by treating x-coordinate changes and y-coordinate changesindependently. For example, the change in the x-coordinate of a singlehand or wrist, Δx=x_(f1)−x_(f2), (where f1 and f2 indicate theimmediately previous frame and the present frame respectively) may bescaled by a factor and may be used to change the x-coordinate of thecenter of the simulated ROI by the absolute or scaled value. The changein the y-coordinate of the single hand or wrist may be analogously andsimultaneously computed and implemented.

Though the methods above are described in terms of the variables x andy, any two coordinates can be utilized in embodiments of the presentinvention, including but not limited to x and y, x and z, or y and z.Axes may be defined such that the y-axis is vertical in the field ofview of the imaging or sensing device, e.g. parallel to a head-to-footline of a standing tracked body, x-axis is horizontal in the field ofview of the imaging or sensing device, e.g. parallel to ashoulder-to-shoulder line of a standing tracked body, and z-axistransverses near-to-far in the field of view of the image of sensingdevice. However, axes may also be defined in any other manner.

Embodiments of the present invention may edit a simulated ROI accordingto relative changes in position(s) between frames, e.g. by followingmethods just described. In embodiments of the present invention usingrelative changes, the entrance of a tracked body part into the controlzone may not immediately edit the simulated ROI. For example, theposition of the simulated ROI may not change to a new location based onwhere in the control zone a tracked hand or wrist entered but mayinstead remain stationary until the tracked hand or wrist moves in thex- or y-direction relative to the coordinates of its entrance; motion ofthe simulated ROI may be relative to the entrance point of the trackedhand or wrist. This feature may contribute to easy and intuitive use ofembodiments of the present invention.

Alternatively, the coordinates of tracked body parts within the controlzone in a given frame, as opposed to relative changes in coordinatesbetween frames, may be utilized to compute the positioning or size of asimulated ROI in X-ray image space. In embodiments of the presentinvention using the coordinates of tracked body parts in this manner,the x- and y-dimensions of the control zone may be proportional to thex- and y-dimensions of the X-ray image or images shown on display 102and may be related to the dimensions of the X-ray image or images by ascale factor. A scale factor relating the dimensions of a control zoneto the dimensions of image(s) on display 102 may be applied to the x-and y-coordinates of a tracked body part within the control zone inorder to determine the image plane coordinates over which the simulatedROI should be positioned. If two tracked hands or wrists are detected inthe control zone, the x- and y-coordinates of the hands or wrists may besimilarly identified and scaled to determine the outer edges of thesimulated ROI in X-ray image display 102. Embodiments utilizing actualcoordinates within the control zone may enable an accustomed user toposition and resize a simulated ROI more quickly than with embodimentsof the present invention utilizing relative changes.

In one embodiment of the present invention, simulated-ROI control 101may be activated only by the detection of tracked body parts, e.g. handsor wrists, being held stationary within the control zone for a givenamount of time, e.g. ⅓ of a second, ½ of a second, ¾ of a second, 1second, 2 seconds, 3 seconds, or 4 seconds, or a non-integer number ofseconds between the enumerated values. If an if/then statement, or anysimilar mechanism, is used in step 53 to relate locations of trackedbody parts with the control zone and activate simulated-ROI control 101,the condition may involve a set number of frames or given amount of timepassing wherein the motion of tracked hands or wrists within the controlzone is below some threshold value. The number of frames or length oftime which must pass for simulated-ROI control 101 to be activated maybe fixed or may be a user option. A benefit of delaying activation ofsimulated-ROI control 101 may be a decrease in the likelihood ofsimulated-ROI control 101 being unintentionally activated; it may belikely that a user passes hands or wrists through the control zone whileperforming aspects of the surgical procedure, and it may be less likelythat the user holds them stationary within the control zone apart fromwhen intentionally activating simulated-ROI control 101.

A similar mechanism may be implemented for deactivation of simulated-ROIcontrol 101. After activation, simulated-ROI control 101 may bedeactivated if a deactivation event is detected e.g. tracked hands orwrists remaining stationary within the control zone for a fixed amountof time. The fixed amount of time resulting in deactivation may be equalto the amount of time used for activation, or may be more or less thanthis amount. For example, the fixed amount of time may be one ⅓ of asecond, ½ of a second, ¾ of a second, 1 second, 2 seconds, 3 seconds, or4 seconds, a non-integer number of second between the enumerated values,or any other length of time. An if/then statement, or other mechanism,governing simulated-ROI control 101 deactivation may depend on relativemotion remaining below a threshold value for a given number of frames oramount of time. Embodiments of the present invention wherein controlzone exit is the sole mechanism for deactivation of simulated-ROIcontrol 101 may require the relative x- and y-positions of tracked handsor wrists to be maintained while withdrawing from the control zone inthe z-direction in order to maintain simulation of a desired ROI size orlocation. The option of deactivating the control zone by holding handsor wrists stationary within the control zone may be desirable for a userconcerned about maintaining simulation of an exact ROI size or location.

The parallel system paths of FIG. 5 meet at step 58, though thepreceding steps may differ slightly. If only x- and y-coordinates aretracked, simulated-ROI editing of step 58 may be enabled by some sort ofswitch in step 57, e.g. a voice-activated switch or physical button.

In step 59 an embodiment of the present invention may allow the user todecide whether or not the changes made to a simulated ROI in step 58should be implemented in the next phase of X-ray image acquisition. Ifchanges made in step 58 are accepted, information sufficient toimplement the simulated ROI may be sent to X-ray imaging system 12. Whenchanges are accepted, information may be passed from processing unit 14to X-ray imaging system 12 as shown in FIG. 1. If changes made in step58 are rejected, information sufficient to simulate the last ROIimplemented by X-ray imaging system 12 may be used to undo all changesmade in step 58. When changes are rejected, information may be passedfrom X-ray imaging system 12 to processing unit 14 as shown in FIG. 1.Any method for the user to accept or reject changes may be used,including but not limited to voice commands; voice-recognition; physicaldevices, e.g. a button, pedal, or mouse; or additional virtual features.Additional contact-free methods of accepted or rejecting changes may berecognition of specific user motions, such as the tracing of apredetermined shape or other sign; definition of additional controlzones that can serve as accept/reject buttons; or any other methodutilizing sensing or imaging device 12 and available tracking units.

If simulated-ROI changes are rejected, but tracked body parts are stilldetected within the control zone and motion-tracking has not beenotherwise switched off, the simulated ROI may be reset to match the ROIcurrently implemented by the X-ray imaging system. If no ROI iscurrently being implemented by the imaging system, the simulated ROI maybe removed and re-defined by subsequently detected motions. Embodimentsof the present invention may allow a user to either begin to edit thesimulated ROI again or switch off simulated-ROI control 101 bywithdrawing from the control zone or by another method.

If changes to the simulated ROI are accepted, they may be passed toX-ray imaging system 12. X-ray imaging system 12 may be capable ofselectively exposing areas of the patient by electronic collimation,mechanical collimation, or some other mechanism, and may implement theselected ROI accordingly.

An X-ray imaging system may be capable of providing varied exposureaccording to more than one defined ROI. Features may be incorporated inembodiments of the present invention that allow users to manipulate morethan one ROI. In one embodiment, additional control zones may be definedand displayed on display 102. These additional control zones may besmaller than the previously discussed, primary control zone andessentially serve as switches determining which one of multiple ROI'swill be controlled if the user enters the primary control zone. Forexample, if two ROI's are being implemented by X-ray imaging system 12,two secondary control zones may be defined and displayed. The secondarycontrol zones may be referenced to the same body point or other point asthe primary control zone and positioned in space outside of the primarycontrol zone, for example to the left or right of the user if theprimary control zone is in front of the user. The system may detect the“touching” of the secondary control zones and select a specificsimulated ROI corresponding to that secondary control zone for editing.The correlation between secondary control zones and simulated ROI's maybe indicated on display 102 using color, e.g. matching the color of theoutline of a simulated ROI to the shading of a secondary control zone,or by any other methods. Detection of a second “touching” of thesecondary control zone may trigger deactivation of simulated ROI controlfor the corresponding simulated ROI.

More than two ROI's may be implemented by X-ray imaging system 12, andmore than two secondary control zones may be defined. Alternatively,other configurations may be used to select one of multiple ROI's. Asingle secondary control zone may be created, and it may switch controlfrom one simulated ROI to another simulated ROI according to apredetermined sequence when a “touch” is detected, using color ondisplay 102 or some other method to indicate which simulated ROI iscontrolled following subsequent “touches” of or motion within thesecondary control zone.

A secondary control zone or secondary control zones may also be providedfor the user to select a shape for the simulated ROI, as previouslydiscussed. A number of secondary control zones may be equal to thenumber of available shapes such that each secondary control zone may beassociated with a given shape, or a there may be a single secondarycontrol zone that can switch the currently simulated ROI to the nextshape in a sequence of available simulated ROI shapes when a “touch” isdetected.

In one embodiment of the present invention, an embodiment of the presentinvention may register user motion as a “touch” by utilizing Booleanstatements similar to those previously discussed for the primary controlzone, e.g. “Hand Entered Control Zone” and “Hand Left Control Zone.”However, directions sent to processing unit 13 may depend on slightlymore complex combinations of these statements. For example, anoccurrence, e.g. a switch from “false” to “true,” of a statement such as“Hand Touched Control Zone” may actually be a combination of multiplestatements such as “Hand Entered Control Zone,” “Hand Remained inControl Zone for X Milliseconds,” and “Hand Left Control Zone.” “HandTouched Control Zone” being “true” may direct processing unit 13 tocontrol a specific simulated ROI. The “X” in “Hand Remained in ControlZone for X Milliseconds” can denote some number of milliseconds,seconds, or other unit of time, for which a tracked hand or wristremaining in the control zone can initiate a “touch” being recorded.This number of millisecond may be 0 to 10 milliseconds, 10 to 20milliseconds, 20 to 30 milliseconds, 30 to 40 milliseconds, 40 to 50milliseconds, 50 to 60 milliseconds, 60 to 70 milliseconds, 70 to 80milliseconds, 80 to 90 milliseconds, 90 to 100 milliseconds, or anyother number of milliseconds within the enumerated ranges, or above.While a statement such as “Hand Touched Control Zone” is true, a similarcombination of statements, e.g. “Hand Entered Control Zone,” “HandRemained in Control Zone for X Milliseconds, and “Hand Left ControlZone,” may switch the statement such as “Hand Touched Control Zone” backto “false” and deselect the given simulated ROI. Any other combinationof statements, events, or other means may be used to enable selection ofa specific simulated ROI for control by processing unit 13 in ahands-free manner.

Alternatively, a foot pedal, voice command, or other physical mechanismmay be used to switch the currently displayed simulated ROI to the nextshape in a sequence of available shapes. Contact-free methods such asrecognition of specific user motions, e.g. the tracing of apredetermined shape or other sign; definition of additional controlzones that can serve as accept/reject buttons; or any other methodutilizing sensing or imaging device 12 and available tracking units mayalso be utilized.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and many modifications andvariations are possible in light of the above teaching. The embodimentswere chosen and described in order to best explain the principles of theinvention and its practical application, to thereby enable othersskilled in the art to best utilize the invention and various embodimentswith various modifications as are suited to the particular usecontemplated. It is intended that the scope of the invention be definedby the claims appended hereto and their equivalents.

What is claimed is:
 1. A method of contactless control of a medicalimaging system comprising: acquiring a medical image from said medicalimaging system; displaying said medical image; tracking a first positionof a first body part of a user; and altering a first aspect of themedical image based on said first position.
 2. The method of contactlesscontrol of a medical imaging system of claim 1 further comprising:determining an altered acquisition parameter for said medical imagingsystem based on alteration of said first aspect; and implementing saidaltered acquisition parameter in said medical imaging system.
 3. Themethod of contactless control of a medical imaging system of claim 1further comprising defining a control zone.
 4. The method of contactlesscontrol of a medical imaging system of claim 3 further comprising:selecting a body reference point on said user; tracking said bodyreference point; and positioning said control zone a fixed distance fromsaid body reference point.
 5. The method of contactless control of amedical imaging system of claim 4 wherein said body reference point ischest of said user.
 6. The method of contactless control of a medicalimaging system of claim 4 wherein said body reference point is head ofsaid user.
 7. The method of contactless control of a medical imagingsystem of claim 4 wherein said body reference point is a midpointbetween two shoulders of said user.
 8. The method of contactless controlof a medical imaging system of claim 1 wherein said first body part is ahand of said user.
 9. The method of contactless control of a medicalimaging system of claim 1 wherein said first body part is a wrist ofsaid user.
 10. The method of contactless control of a medical imagingsystem of claim 1 wherein said first aspect is a location of a region ofinterest in said medical image.
 11. The method of contactless control ofa medical imaging system of claim 1 further comprising: defining acontrol zone; establishing a set of image options for said medicalimage; monitoring said first position with respect to said control zone;and switching between image options of said set if said first positiontouches said control zone.
 12. The method of contactless control of amedical imaging system of claim 11 wherein said image options are shapesfor a region of interest in said medical image.
 13. The method ofcontactless control of a medical imaging system of claim 1 furthercomprising: tracking a second position of a second body part of saiduser; and altering a second aspect of the medical image based on saidfirst position and said second position.
 14. The method of contactlesscontrol of a medical imaging system of claim 13 wherein said secondaspect is a size of a region of interest in said medical image.
 15. Acontactless control system for medical imaging comprising: a sensingdevice configured to sense a user; a first processing unit coupled tosaid sensing device; a tracking unit in said first processing unit fordetermining a first position of a first body part of said user; a secondprocessing unit coupled to said first processing unit; a medical imagingsystem coupled to said second processing unit; a display coupled to saidmedical imaging system for displaying a medical image; and a controlunit in said second processing unit for controlling said medical imagingsystem.
 16. The contactless control system of claim 15 furthercomprising a second tracking unit for determining a second position of asecond body part of said user.
 17. The contactless control system ofclaim 15 wherein said second processing unit is configured to define acontrol zone within a field of view of the sensing device.
 18. Thecontactless control system of claim 17 further comprising a seconddisplay configured to show said first position and said control zone.19. The contactless control system of claim 15 further comprising asecond tracking unit configured to track a body reference point on saiduser.
 20. The contactless control system of claim 15 wherein saidmedical imaging system comprises a radiation source configured todeliver higher radiation flux to a region of interest than to otherregions.